TLR9 and infection: Moreover, MEFs isolated from wild-type, TLR-9−/−, TLR-3−/−, MAVS−/− and MyD88−/− and TRIF−/− C57BL/6 mice embryos were all producing similar levels of IFN-β upon MVMp infection (Figure 4B), indicating that neither TLRs nor RLRs are involved in the IFN response triggered by replicating MVMp in MEFs.